Indicia bearing electrolluminescent panel and method of manufacture



Jan. 26, 1960 J. D. MILLER INDICIA BEARING ELECTROLUMINESCENT PANEL ANDMETHOD OF MANUFACTURE Filed Jan. 5, 1959 FI c. I0

1N V EN TOR. (/a/m/ @A W50/v /W/L fe aan@ 4 TToE/VE rs United A*StatesVPatent INDICIA BEARING ELECTROLUMINESCENT PANEL AND METHOD F MANUFACTURE John Dawson Miller, Alhambra, Calif.

Application January 5, 1959, Serial No. 785,058

8 Claims. (Cl. 313-108) This invention relates to indicia bearingelectroluminescent panels and to a method of manufacture, and includedin the objects of this invention are:

First, to provide an electroluminescent panel and method of manufacturewherein an electroluminescent panel of standard dimension may be treatedto remove selected coatings therefrom in predetermined regions, wherebythe panel may be punched, bent, or otherwise shaped as desired withoutdamage to the remaining coatings, and wherein removal of the coatingsmay bel so predetermined as to provide luminescent and non-luminescentareas, either of which may constitute indicia'and the other background.

Second, to provide an electroluminescent panel and method of manufacturewhich eliminate preforming or punching of the metal Iblank beforeapplication of the various coatings which produce electroluminescence sothat the manufacture of the panel may produce standard panels for laterconversion into indicia bearing panels.

Third, to provide an electroluminescent indicia bearing panel in whichthe capability of producing luminescence in the non-luminescent areas isdestroyed rather than beingmerely-covered so that any scratching of thesurfacek will not expose an underlying luminescent layer.

With the above and other objects in View, as may appear hereinafter,reference is directed to the accompanying drawings in which:

Figure 1 is a substantially diagrammatical, fragmentary, perspectiveview of a panel incorporating one form of the invention;

Figure 2 is a further enlarged, sectional View through 2--2 of Figure l;

Figure 3 is a similar fragmentary, sectional view through 3 3 of Figurey1;

Figure 4 is a substantially diagrammatical, fragmentary, sectional viewshowing a modified form of the invention;

Figure 5 is a similar fragmentary, sectional view showing a furthermodified form of the invention;

Figure 6 is another similar fragmentary, sectional view showing a stepinvolved in the manufacture of another Aform of the invention;

Figure 7 is a similar fragmentary, sectional View showing a further stepin the manufacture of the construction shown in Figure 6; v

Figure 8 is a Iplan view of a panel incorporating the construction shownin Figures l, 2, and 3;

Figure 9 is a fragmentary plan View of a panel incorporating theconstruction shown in Figure 4;

Figure l0 is a fragmentary plan view of a panel showing the constructioncorresponding to Figures 6 and 7;

Figure ll is an enlarged fragmentary, sectional view through 11-11 ofFigure 8 showing one manner in which the panel may be connected to asource of electrical energy;

Figure 12 is a fragmentary, substantially diagrammatical, sectional viewtakenthrough 12--12 of Figure 1.

The presentA invention utilizes as a blank a prepared luminescent panelor lamp which `comprises a base mem'- ber 1, of vitreous enamelingsteel, which serves as one conductor of the lamp or panel and providesmechanical strength and physicalrigidity to the completed structure. Thesteel base member 1`receives a base coating 2. of ceramic material, suchyas white porcelain, which constitutes an insulation layer.

Over the base coating or insulation layer 2 there is applied a coating 3of an electroluminescent'phosphor impregnated in a ceramic material.Overthe electroluminescent coating 3 there is applied a transparentelectricallyconducting coating or layer 4. Overthis layer is applied afourth coating or layer of transparent insulation 5. This may beglass-like.

The steel base member 1 and the transparent electri` cally conductinglayer 4 serve as the plates of a condenser, whereas the base ceramiclayer 2 and electroluminescent phosphor layer 3 constitutes thedielectric of the condenser. When the steel base member 1 andtransparent electrically conducting layer 4 are connected to a source ofalternating currentl'ight is emitted from the dielectric-phosphor layer.The transparent insulating layer 5 of glass protects the other layers,particularly the dielectric-phosphor layer 3, from the effects ofhumidity and mechanical damage, and also provides an insulating outersurface. 'I'he coatings are quite thin, the sum of the thicknesses ofall ofthe coatings being less than one-ftieth of an inch. In thedrawings, these layers are necessarily greatly exaggerated in thickness.

Reference is directed particularly to Figures l, 2, 3, and 8. In theconstruction here illustrated, the luminescent portion of the panel isutilized as a background, and indicia as represented by the word OUT inFigure 8 is without electroluminescence. This is accomplished bySandblasting, chemical etching, or otherwise cutting through thetransparent layer 5 and electrically conducting layer 4 to form relievedareas or channels 6.

The relieved areas or channels 6 are partially filled with a conductivecoating 7. This may be a conductive paint.

The conductive coating 7 is sufficiently deep to provide electricalconnection with the conducting layer 4 so that, for example, the centralpart of the O in Figure 8 is electrically connected to the surroundingconducting layer. The coating 7 need not be continuous throughout therelieved areas 6, although as a matter of convenience the coating may becontinuous. The conductive coating 7 is opaque so that there is Vnotransmission of luminescence from the underlying phosphor impregnatedcoating or layer 3. The conductive coating 7 isk covered by aninsulating filler 8 which may completely iillthe relieved areas 6. Theinsulatingifil-ler 8 may have a color contrasting with the surroundingpanel so that under daylight conditions, without ultilization ofVelectroluminescent phosphor,` the indicia is clearly visible. -Under`conditions of operation in darkness, theluminescent panels surroundingthe relieved areas 6 glow, whereas the relieved areas 6 are dark.

Reference is now directed to Figures 4 and 9. In this construction, theluminescent area constitutes the indicia and the non-luminescent areaconstitutes the background. As in the construction of the panel shown inFigure 8, relieved areas 9 are formed by Sandblasting, chemical etching,or mechanically cutting away the various layers. In this case, thetransparent insulating layer 5transpar'ent electrically conducting layer4,` and phosphor impregnated layer 3 are removed, leaving the majorportion of the base ceramic coating 2 intact. The .relieved areas thusform luminescent raised areas 10. Again, it should be noted that thethickness of the layers is greatly exaggerated. so that the raised areas10 are only a. few thousandths of an inch above the relieved areas 9. Inorder that all of the'raised areas be luminescent, it is of coursenecessary that they be electrically connected. This may be done inseveral ways, as, for example, in Figure 9 where the letters IN arejoined by a common base b ar 11.

Reference is now directed to Figure 5. In this case,

thefrelieved areas correspond to the relieved areas 9, but, instead ofretaining the ceramic base coating 2, all four coatings are removed inthe relieved areas exposing the steelbase member 1. The relieved areasare then covered by' an 'insulating coating 12, such as an enamel. Thecoating 12 i `s preferably applied in such a manner that a meniscus 13is formed around the margins of the raised areas so as to insulate thetransparent electrically conducting layer 4 from the base member 1. Inthe arrangement shown in Figure 4, the ceramic base coating 2 performsthis function.

Reference is now directed to Figures 6, 7, and 10. In the constructionof the panel here illustrated, those areas which are to become theluminescent raised areas 14 are covered with an initial protectivecoating 15 so as to mask these portions of the panel. The transparentinsulating layer 5, transparent electrically conducting layer 4, andphosphor impregnated layer 3 are then sandblasted, etched, or otherwiseremoved in the manner similar to yFigure 4 leaving the ceramic basecoating 2.

A second protective coating 16 is applied over the so that the panel maybe bent or otherwise formed in the area from which the coatings orlayers have been removed.

It will be observed that the method of manufacture of the panel isessentially the same in each of the constructions shown; that is, ineach instance a panel blank is provided having the vvarious coatings orlayers uniformly distributed thereover. The areas to remain luminescent,whether they be background areas or indicia-forming areas, are suitablyprotected, for example, by a protective coating. The remaining areaswhich are to be non-luminescent are treated to remove at least thetransparent insulating layer 5 and the transparent electricallyconducting layer 4.

This basic method vis modified as in Figures 1, 2, 3, and 8 bycompletely or partially covering the nonluminescent areas with aconductive coating 7 and then t filling the non-luminescent areas with asuitable insulatraised areas and for a predetermined distance over the fceramic base coating 2 around the raised areas to form marginal areas17. The unprotected portions of the ceramic vbase coating 2 are thenremoved. After the protective coatings 15 and 16 are cleaned from thepanel, each of the luminescent areas is surrounded by a marginal area ofthe base coating 2 which serves to insulate the transparent electricallyconducting layer 4 from the base member 1. It should be noted that thethickness of the ceramic base coating 2 and the phosphor impregnatedcoating 3 are of insuflicient thickness to prevent arcing if thetransparent electrically conducting layer 4 is exposed at its edgesdirectly above the base member. The marginal areas 17 ensure an adequateminimum spacing between the exposed edges of the conducting layer ,andthe base. As a practical example, the marginal portion 17 may beapproximately one-sixteenth of an inch wide.

The manner of providing electrical connections with the base member 1and conducting layer 4 may be conventional. By way -of example, the basemember 1 may be provided with a ground terminal 18 and an insulatedterminal 19, the insulated terminal 19 being connected by a contactspring 20 to a conductive strip 21 in electrical contact with theconducting layer 4. The conductive strip 21 may be applied within arelieved area similar to the relieved area 6 from which the transparentinsulating layer 5 has. been removed. The conductive strip 21 may be inelectrical contact with the underlying transparent conducting layer 4,or its margins may contact the edges of the layer if the etching haspenetrated this lay'er.

It is not only desirable to sandblastvor etch, or otherwise remove, `thecoatings from those areas which are to form indicia in a luminescentbackground or luminescent letters on a dark background, but also toprovide for various forming and punching operations on the panel. If,for example, it is desired to provide mounting holes, the coatings orlayers are etched away in the area of the hole and for a limi-tedmarginal distance clear of the hole in the manner shown in Figure 5 orin Figures 6 and 7. After this is done the hole may be punched in thebase member 1. The portion of the panel needed for the mounting of theterminals 18 and 19 may be similarly prepared. Still further, if it isdesired tofold the panel, the region along the intended fold line issandblasted or etched so as to remove the various layers, as shown inFigures 1 and 12,

ing and preferably opaque filler 8. This method is primarily suited forthe production of non-luminescent indicia on a luminescent background.

If the reverse condition is desired, merely luminescent indicia on anon-luminescent background, the methods shown in Figures 4, 5, 6, 7, 9,and l0 are employed. In these methods the non-luminescent areas areformed by removing the layers to the base coating 2, as in Figure 4, orto the steel base member 1, as in Figure 5, then coating thenon-luminescent layer with suitable insulating material 12. In thiscase, the margins of the raised portions are protected by the meniscus13 coating the vertical edges of the raised portions.

A further modified method of forming raised lumiz nescent portionsinvolves rst masking the luminescent portions to be retained, partiallyremoving the coatings to expose the base ceramic coating 2, then maskingthe base ceramic portion to the marginal areas around the luminescentportions, and completing the etching or removing process -in theluminescent areas until the steel base member 1 is exposed. It of coursefollows that if the steel base member 1 is exposed, a protective coatingthereover will be required, and such coating is preferably transparentso that it may be sprayed over the entire panel.

The method of manufacture also includes lthe steps of removing thelayers to the base metal for the purpose of punching, bending, orotherwise treating or shaping the base member 1.

While particular embodiments of this invention have been shown anddescribed, it is not intended to limi-t the same to the exact details ofthe constructions set forth, and it embraces such changes,modifications, and equivalents of the parts and their formation andarrangement as come within the purview of the appended claims.

What is claimed is:

l. An electroluminescent structure comprising a continuous metal basehaving successive coatings of; an insulating layer, a phosphor bearinglayer, a transparent conductive layer, and a transparent insulatinglayer, and a source of electrical energy connected to said base andconductive layer, at least said phosphor-bearing layer being removedfrom predetermined areas whereby said areas are non-luminescent.

2. An electroluminescent structure' comprising a continuous metal basehaving successive coatings of; an insulating layer, a phosphor bearinglayer, a transparent conductive layer, and a transparent insulatinglayer, and a source of electrical energy connected to said base andconductive layer, at least said transparent layers being removed frompredetermined areas whereby said areas are non-luminescent; and a llerfor said nonluminescent areas including conductors bridging betweenedges of said transparent conductive layer.

3. A method of producing an indicia bearing electroluminescent structurefrom an electroluminescent blank panel wherein a metal base is coatedsuccessively with an insulating base layer, a phosphor bearing layer, atransparent conductor layer, and a transparent insulating layer, thesteps comprising: removing portions of at least said transparent layersto form non-luminescent areas on said panel.

4. A method of producing an indicia bearing electroluminescent structurefrom an electroluminescent blank panel wherein a metal base is coatedsuccessively with an insulating base layer, a phosphor bearing layer, atransparent conductor layer, and a transparent insulating layer, thesteps comprising: removing portions of at least said transparent layersto form non-luminescent areas on said panel; bridging saidnon-luminescent areas with a conductor: means; and applying a coating ofinsulating material over said conductor means.

5. A method of producing an indicia bearing electroluminescent structurefrom an electroluminescent blank panel wherein a metal base is coatedsuccessively with an insulating base layer, a phosphor bearing layer, atransparent conductor layer, and a transparent insulating layer, thesteps comprising: removing portions of said layers to expose saidinsulating base layer thereby to divide said panel into luminescent andnon-luminescent areas.

6. A method of producing an indicia bearing electroluminescent structurefrom an electroluminescent blank panel wherein a metal base is coatedsuccessively with an insulating base layer, a phosphor bearing layer, atransparent conductor layer, and a transparent insulating layer, thesteps comprising: removing portions of said layers to expose said metalbase thereby to divide said panel into luminescent and non-luminescentareas; and coating said metal base.

7. A method of producing an indicia bearing electroluminescent structurefrom an electroluminescent blank panel wherein a metal base is coatedsuccessively with an insulating base layer, a phosphor bearing layer, atransparent conductor layer, and a transparent insulating layer, thesteps comprising: removing portions of said layers to expose saidinsulating base layer and divide said panel into luminescent andnon-luminescent areas; and removing portions of said exposed insulatingbase layer to form borders around said luminescent areas.

8. A method of producing an indicia bearing electroluminescent structurefrom an electroluminescent blank panel wherein a metal base is coatedsuccessively with an insulating base layer, a phosphor bearing layer, atransparent conductor layer, and a transparent insulating layer, fthesteps comprising: removing portions of said layers to expose said metalbase thereby to divide said panel into luminescent and non-luminescentareas; and performing work operations on said exposed metal base.

References Cited in the le of this patent UNITED STATES PATENTS2,721,808 Roberts et al. Oct. 25, 1955 2,755,406 Burns July 17, 19562,773,216 Edmonds Dec. 4, 1956 2,790,161 Ioormann Apr. 23, 19572,847,602 Michlin Aug. 12, 1958

